Predicting HPAI epidemic impact on Southern Elephant Seals
A study published in Marine Mammal Science examines the profound implications of a recent outbreak of the H5N1 avian influenza virus on the southern elephant seal (Mirounga leonina) colony at Península Valdés, Argentina. Over two decades, this population experienced a modest growth rate of 0.9%, culminating in approximately 18,000 reproductive females by 2022. However, the sudden onset of the H5N1 epidemic in 2023 led to alarming mortality rates among pups and adults, prompting an urgent need to model the potential long-term effects on population dynamics. Key findings indicate that while the loss of newborn pups had a relatively minor effect on the overall population due to their naturally high mortality rates, adult female mortality presented far more significant and immediate consequences. The research suggests that the impact of pup deaths would not manifest until 2027, when those pups would have reached maturity and begun reproducing. Conversely, increased mortality among mature females could drastically reduce breeding populations as early as 2024. The estimated recovery time ranges from 2035 in less severe cases to over a century in the most dire scenarios involving substantial adult mortality and reduced reproductive success.
In late 2023, Península Valdés in Argentina experienced a major outbreak of highly pathogenic avian influenza (H5N1) among wild animals. This was part of a broader wave of H5N1 (clade 2.3.4.4b) that spread through South American wildlife starting in 2022 (1). The Península Valdés outbreak was unprecedented in scale, affecting both marine mammals and seabirds and causing mass mortality in the region.
1. Uhart MM, Vanstreels RE, Nelson MI, Olivera V, Campagna J, Zavattieri V, Lemey P, Campagna C, Falabella V, Rimondi A. Epidemiological data of an influenza A/H5N1 outbreak in elephant seals in Argentina indicates mammal-to-mammal transmission. Nature Communications. 2024 Nov 11;15(1):9516.
